The present invention relates to a solenoid coil assemblies and more particularly, to a design configuration and method for securing solenoid coils relative to corresponding valve assemblies.
Solenoid actuated valves are manipulated in response to an electromagnetic force of the solenoid coil. The electromagnetic force positions movable valve elements in various manners. An integral part of these devices are the air gaps provided in the electromagnetic circuit of the solenoid. A primary (working), air gap is generally provided between the movable armature and a first non-moving ferromagnetic element. The first non-moving ferromagnetic element generally comprises an integral part of the associated valve""s structure. Secondary (parasitic) air gaps are generally provided between the movable armature and other non-moving ferromagnetic elements. The other non-moving ferromagnetic elements generally comprise integral parts of the actuator. When the solenoid is energized, the coil establishes magnetic flux in the ferromagnetic elements which traverses all the air gaps. The size of the air gaps is an important factor in determining the operational characteristics of the device.
Variations in the magnetic flux transfer properties of solenoid actuated valves may be particularly intolerable depending upon the nature of the application within which the device operates. Efficient designs must prevent magnetic flux losses created by undesirable conditions such as inordinately large secondary air gaps.
In some applications a solenoid actuator may be incorporated with a control mechanism by directly attaching the solenoid""s coil terminal pins to a circuit board. In this type of device, the solenoid actuated valve comprises two subassemblies. One subassembly carries the actuator""s coil with its terminals soldered to the control circuit board. The other subassembly carries the valve body. When the two subassemblies are mated together, some facility is generally provided for allowing the coil to move relative to its subassembly and into position for receipt onto the valve body. However, since the coil is preferably soldered to the circuit board prior to mating of the two subassemblies, connection of the coil and valve body may undesirably stress the soldered connections between the coil""s terminal pins and the circuit board due to, for example, slight mislocations of the positioning of both subassemblies from normal manufacturing tolerances.
Provisions that allow movement of the coil for assembly purposes may also become undesirable when the solenoid actuated valve is placed in service. Coil movement may be induced by vibratory conditions that exist in the solenoid actuated valve""s operating environment. Vibration induced coil movement also transfers loads to the soldered terminal pin connection.
Therefore, a solenoid actuated valve""s design should prevent this condition from occurring. Accordingly, a solenoid actuated valve design is required that: provides ease of assembly and disassembly, exhibits good magnetic flux transfer characteristics, and is able to withstand harsh vibratory environments.
It is a goal of the present invention to provide a solenoid actuated valve that: is constructed from two subassemblies that are easily assembled and disassembled, exhibits good magnetic flux transfer characteristics, and is able to withstand harsh vibratory environments. In accordance with this goal, a solenoid actuated valve is provided that is designed according to concepts that are equally applicable to normally closed valves, normally open valves, multi-function valves, and other typical related types of valves. The solenoid actuated valve includes a first subassembly that carries a coil having its terminal pins attached to a structure such as a circuit board or rigid lead frame. A second subassembly is provided for mating with the first subassembly. The first and second subassemblies carry the valve body which may be further attached to a valve housing utilized for directing the flow of hydraulic fluid.
In accordance with a preferred embodiment of the present invention, a first subassembly includes a solenoid spool including the coil and the second a case for surrounding the spool.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.